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Arms that "bottom out" - Operator Preferences


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#1 Jamie Northrup

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Posted 22 July 2013 - 03:48 PM

I'm in the market for a new arm and I (briefly) tested out a PRO and an Artemis arm.  However, there is one thing I'm not used to and I was hoping someone could shed some light upon.

 

When the arm (either arm) reaches the bottom of it's boom range, it just stops.  The stop isn't feathered out by the spring reaching the end of it's range.  There is no change in the force required to push it further.

 

That isn't something I'm used to, so it's very strange to me.  I'm used to an arm that pushes back at the end (even when properly set up).  I'm curious about everyone's opinions on this.  

 

 

Is that just something that you get used to?

Does hitting the bottom every hurt/ruin your shot?

Do any other operators share my preference resistance at the end of the boom range?

 

 


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#2 Chris Poynton

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Posted 22 July 2013 - 04:47 PM

I would love to see Lift Performance Curves from the major manufacturers so that new purchasers in particular can compare "apples with apples" for various arms. Curves would show whether the arm is progressive/buffered at the extremes, iso-elastic characteristics under a wide range of loads, and common expectations for how many pounds/kg of lift should be required with various arm settings.

 

If anyone has any such formal data or graphs, even from ancient dusty archives, I am way keen to absorb this, so please post or PM. 

 

I have been giving a lot of thought as to what a user friendly, industry standard format for lift curves might look like. My mock-ups of "iso v non-iso" curves, as well as proposed basic test methodology for lift performance is at: www.cp.org.au/movies/steadicam-test.html#lift_curves ... (That steadicam testing page was put together to help new purchasers wade through some of the lingo and pitfalls of low-end systems, but the lift performance stuff may be relevant to higher-end systems, due to the gaping absence of this data in the marketplace).


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#3 Twojay Dhillon

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Posted 22 July 2013 - 09:05 PM

Curves shmurves... Point the glass and shoot. Too much technical BS on here nowadays. Work with an arm long enough and you'll have muscle-memory for the range, both up and down. Paralysis through analysis: avoid it like the f'ing plague.
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#4 Twojay Dhillon

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Posted 22 July 2013 - 09:06 PM

Oh, and buy PRO. ONCE. Last arm you'll ever buy.
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#5 Ants Martin Vahur

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Posted 30 July 2013 - 08:32 AM

Hi!

 

I'm very happy with my Master Series arm thus far. But I'm also annoyed by the bottoming out. Especially when one joint, usually the one closer to the vest, bottoms out and then "un-bottoms" there will be a jolt in the arm movement which delegates into the shot, when dealing with slow movement.

I'm not much of a craftsman, but a dampening system would be great.

 

Another thing with Master arm is that it's ISO is "negative" in the sense, that on Chris's dampening chart it would go to the left to the negative pound values when lifting or descending the load.

 

Ants Martin

 

I'm in the market for a new arm and I (briefly) tested out a PRO and an Artemis arm.  However, there is one thing I'm not used to and I was hoping someone could shed some light upon.

 

When the arm (either arm) reaches the bottom of it's boom range, it just stops.  The stop isn't feathered out by the spring reaching the end of it's range.  There is no change in the force required to push it further.

 

That isn't something I'm used to, so it's very strange to me.  I'm used to an arm that pushes back at the end (even when properly set up).  I'm curious about everyone's opinions on this.  

 

 

Is that just something that you get used to?

Does hitting the bottom every hurt/ruin your shot?

Do any other operators share my preference resistance at the end of the boom range?

 

 


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#6 Chris Poynton

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Posted 30 July 2013 - 10:25 AM

On the "draft of iso-elasticity curves" diagram, all the lift values are shown as "positive" merely to compress the space required for the display of data. (i.e. pushing the arm down below the float point requires "negative lift" of x pounds, but is shown as a positive value.) I will make a note on the digram if/when I update it. Sorry for any confusion.


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#7 Eric Fletcher S.O.C.

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Posted 30 July 2013 - 06:20 PM

I would love to see Lift Performance Curves from the major manufacturers so that new purchasers in particular can compare "apples with apples" for various arms. Curves would show whether the arm is progressive/buffered at the extremes, iso-elastic characteristics under a wide range of loads, and common expectations for how many pounds/kg of lift should be required with various arm settings.

 

If anyone has any such formal data or graphs, even from ancient dusty archives, I am way keen to absorb this, so please post or PM. 

 

I have been giving a lot of thought as to what a user friendly, industry standard format for lift curves might look like. My mock-ups of "iso v non-iso" curves, as well as proposed basic test methodology for lift performance is at: www.cp.org.au/movies/steadicam-test.html#lift_curves ... (That steadicam testing page was put together to help new purchasers wade through some of the lingo and pitfalls of low-end systems, but the lift performance stuff may be relevant to higher-end systems, due to the gaping absence of this data in the marketplace).

 

First off no such thing as a "Lift performance curve" it's a force curve nothing more. And honestly it won't tell the masses much about the arms. 99.999999% of the drivers in the world can't read a shock dyno graph but they can drive a car and tell you if they like the ride or the way that it handles. Hell, even a majority of the Professional race drivers I coach can't read a shock sheet.  Then lets talk about the fact that Tiffen is using a word that is made up and doesn't really explain what is going on with an arm (and no the wikkipedia entry written BY tiffen doesn't count as proof that it's a real term. It's actually and economic term) Arms are either Progressive (the PRO arm) or Digressive (the tiffen made up word arms) A bit of an explanation is here http://www.steadicam...c=15133&p=71590  

 

 

On the "draft of iso-elasticity curves" diagram, all the lift values are shown as "positive" merely to compress the space required for the display of data. (i.e. pushing the arm down below the float point requires "negative lift" of x pounds, but is shown as a positive value.) I will make a note on the digram if/when I update it. Sorry for any confusion.

 

And this is what I'm talking about, even you don't understand what you are trying to present a tool to evaluate arm performance. Reading a chart won't give you an answer Actually flying the arm will.  

 

Another observation, Chris you are building a rig and from your own admission you haven't really flown a big rig, what leads you to believe that you are qualified to write a buyers/testing guide?  As it is each of your information panels has HUGE errors in it.  Take for instance your assumption of arm performance. The PRO arm does not "Bounce back" and takes no additional training or mental energy to operate.  


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#8 Eric Fletcher S.O.C.

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Posted 30 July 2013 - 06:22 PM

I'm in the market for a new arm and I (briefly) tested out a PRO and an Artemis arm.  However, there is one thing I'm not used to and I was hoping someone could shed some light upon.

 

When the arm (either arm) reaches the bottom of it's boom range, it just stops.  The stop isn't feathered out by the spring reaching the end of it's range.  There is no change in the force required to push it further.

 

That isn't something I'm used to, so it's very strange to me.  I'm used to an arm that pushes back at the end (even when properly set up).  I'm curious about everyone's opinions on this.  

 

 

Is that just something that you get used to?

Does hitting the bottom every hurt/ruin your shot?

Do any other operators share my preference resistance at the end of the boom range?

 

 

Ummm that not the performance characteristic of either of those arms


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#9 Ken Nguyen

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Posted 30 July 2013 - 09:59 PM

I second Eric and Twojay.


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#10 Chris Poynton

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Posted 31 July 2013 - 12:23 AM

A PRO arm curve could be sketched against Tiffen Gx/Masters arms (by anyone who has operated them) so as to put all this on paper so we are speaking the same language. (I have not flown either). Those curves would illustrate the practical difference between progressive/digressive  and iso/non-iso performance and perhaps partly resolve the original question of this thread.

 

If established operators are happy with their arms, that is fantastic. They may have no need/interest to talk about data. Good luck. But there are plenty of aspiring ops who are not in that position.

 

The starting point for my attempts to draw "lift performance curves" is that no such data is released by manufacturers, so there is no industry standard or conventions for presentation. Even basic definitions of iso-elasticity are squabbled over endlessly on forums, even by the highest end professionals (to wit Eric's link). Even strict patent definitions leave plenty of room for discussion. Entry-level users are not in a position to road-test numerous arms, unless they are very well connected and happen to live in major production centers. "Feel" of arms is a subjective preference. The challenge for new purchasers is to efficiently compare "apples with apples" and make purchasing choices based on cost/benefit analysis of features and performance.

 

To answer a couple of Eric's points ... I have flown large rigs, but only at a workshop many moons ago and my muscle memory recall is not very precise. I have recently done more extensive data testing on a Flyer, as well as various low-end Chinese arms. I have put together my webpage in a serious effort to assist other aspiring prosumers in a similar position to myself who wish to compare performance parameters of low-end brands against industry leading brands. (e.g. when various people on forums buy new Laing or Proline or L'Aigle systems for a few grand, how can we test the arms using a precise methodology, share data and then compare performance against the known "industry standard"  mid/high-end  arms).  As noted on my website, I have asked for corrections and contributions wherever possible ... it is a work in progressive and a learning curve in itself, tackled cautiously.

 

Lift/force is one aspect of the arm's performance/feel, and I appreciate that there are other crucial factors such as internal friction (e.g. as per the "toe test") ... but again there is a dearth of available data or clear conclusions from the field for various models that we can access at present.


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#11 Eric Fletcher S.O.C.

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Posted 31 July 2013 - 12:40 AM

Chris, you are missing the point, arm performance is about feel, not a curve on a sheet of paper. Besides to understand and correlate whats on the page you need to actually know what they feel like, meaning you would have actually had to have flown the arms.  the other thing is you make some pretty broad assumptions on geometry. What are you basing your observations on?  if you havn't flown the arms or the rigs what exactly do you know or understand about what works and what doesn't? Flying a large rig at a workshop doesn't really mean that you have the experience to make observations on it's performance (to the advantage of some companies)


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#12 Benjamin Treplin

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Posted 31 July 2013 - 02:52 AM

Hi Chris,

I'm all with Twojay and Eric. No curve or chart will tell how an arm performs while you operate it. It just doesn't translate into a feeling. It's the same with lenses. No chart will tell you what the images looks like a zoom or prime lens will project onto film or the sensor. There are lenses that have terrible test chart results, bad resolution, chromatic aberration and utter torsion, but for all that just look gorgeous on the screen.

 

To answer you question Jamie.

Is that just something that you get used to? - Yes

Does hitting the bottom every hurt/ruin your shot? - Depends
Do any other operators share my preference resistance at the end of the boom range? - No, I don't. A feathered stop just reduces the useable boom range of the arm while in motion. It is not a feature, it's a bug!

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#13 Jens Piotrowski SOC

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Posted 31 July 2013 - 08:17 PM

"But I'm also annoyed by the bottoming out. Especially when one joint, usually the one closer to the vest, bottoms out and then "un-bottoms" there will be a jolt in the arm movement which delegates into the shot, when dealing with slow movement."

 

fix: You have to adjust both sections of the arm that they are reaching their bottom limit at the same time.

 

Another note on the arms:

 

I've owned both the Tiffen master series and now the PRO arm. The PRO arm does not get stuck at the limits like the Tiffen arm. Plus, again like Eric and Benjamin said, it's all about feel and muscle memory.

 

I never reach the bottom limit of my arm because me legs adjust accordingly, the sled will hit the ground first...


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#14 Alec Jarnagin SOC

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Posted 01 August 2013 - 12:23 AM

BMW, Audi, Mercedes? Toyota, Honda, or Chevy? Curves? No! Test drive.
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#15 Eric Fletcher S.O.C.

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Posted 01 August 2013 - 12:37 AM

BMW, Audi, Mercades? Toyota, Honda, or Chevy? Curves? No! Test drive.

 

mercedes......


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